This invention relates to laparoscopic forceps, particularly to the handle of such forceps.
Laparoscopic forceps conventionally comprise a handle, a tubular housing carrying an actuator mechanism and a forceps jaws mechanism located at the remote end of the tubular housing. Manual actuation of the handle opens or closes the jaws. The shaft and jaws mechanism may be rotated relative to the handle and a ratchet mechanism may be provided to allow clamping of the jaws. A monopolar diathermy connection may be provided to facilitate cauterisation of tissue clamped by the jaws. In conventional laparoscopic forceps the handle comprises a pistol grip arrangement wherein the diathermy connection extends upwardly so that the power cable extends from the handle over a surgeon""s hand adjacent the knuckles or thumb. The pistol grip arrangement makes it necessary for a surgeon to raise or lower the elbow in order to rotate the forceps in use. This is inconvenient and can be tiring, particularly as the diathermy cable may pass over the surgeon""s elbow.
According to the present invention a laparoscopic forceps comprises a handle; a tubular housing extending axially from the handle and carrying an actuator rod; a jaws mechanism disposed at the end of the tubular housing remote from the handle engaged to the actuation rod and arranged so that the jaws may be opened or closed by actuation of the handle; wherein the handle comprises left and right bow members pivotally connected to a mounting core in a scissors-like arrangement, and adapted to engage a user""s finger and thumb in use; the forceps including a switchable ratchet mechanism moveable between locked and unlocked positions, adapted when locked to allow closure and prevent opening of the jaws, and when unlocked to allow free opening and closing of the jaws.
Laparoscopic forceps in accordance with the present invention confer the advantage that the operation and positioning of the jaws may be controlled by the thumb and one finger of the surgeon, leaving fingers free for operation of the switchable ratchet mechanism or other tasks.
The construction and function of the forceps of this invention may be considered conveniently with the scissor-like bows generally horizontal so that a surgeon""s hand is in the prone position with palm downwards during use.
The switchable ratchet mechanism preferably incorporates a finger operable switch member. The switch member is preferably located on the upper side of the mounting core of the handle. In preferred embodiments the switch extends longitudinally of the handle, and is engaged by a pivot at the rear end thereof between the bows, the front end being pivotable laterally to switch the mechanism between the first and second positions.
The switch member may be conveniently actuated by a surgeon""s index or second finger without losing control of the jaws of the forceps.
The ratchet mechanism may conveniently include a rack carried by a first bow member and a pawl carried by the second bow member, the rack and pawl being engaged in the locked position of the mechanism and disengaged in the unlocked position.
A spring is preferably arranged to urge the pawl into engagement with the ratchet. Alternatively a spring may urge the ratchet into engagement with the pawl.
In preferred embodiments the switch member includes a formation adapted to form a cam surface extending rearwardly of the pivot to engage a surface of the pawl adapted to form a cam follower; arranged so that the movement of the switch member from the locked to unlocked position urges the pawl away from the ratchet against the action of the spring to disengage the pawl and ratchet. The cam surface may be conveniently provided by a pin or stud depending from the body of the switch.
In an alternative arrangement the cam surface of the switch member may engage the ratchet to urge the latter out of engagement with the pawl. It is desirable that a surgeon can quickly or temporarily release the locking mechanism without need to actuate the switch. Accordingly in an especially preferred embodiment of the invention the switch member may be secured by the pivot to a slideable release member, the release member being mounted to allow axial movement between first and rear positions with respect to the core; wherein in the first position the ratchet member may be moved between the locked and unlocked positions and in the rear position the pawl is released from the ratchet.
The release member may have an upward projection defining a forwardly facing finger grip or other manual engagement surface. Thus a surgeon may easily retract the release member to temporarily disengage the ratchet and pawl. Removal of the surgeon""s finger re-engages the locking mechanism.
It is important to note that a single spring acting on the pawl not only engages the pawl with the ratchet but also provides the restoring force urging the sliding member into the forward rest position. This economy of construction facilitates assembly and reduces the number of stressed components employed.
The release member and switch are conveniently disposed longitudinally on the upper centre portion of the handle, to allow easy access. The forward facing engagement surface and upper surface of the switch preferably define a continuous, smooth profile. The forward end of the switch may abut with the release member and cooperate with it to provide a click-stop mechanism or over centre arrangement to prevent accidental dislodgement of the switch during use.
The convenient manipulation of the scissor-like handle and controls afforded by the forceps of this invention gives a surgeon greater freedom to manipulate rotation of the jaws. Rotation through 180xc2x0 as a single movement is facilitated. As the jaws are bilaterally symmetrical complete freedom of angular orientation of the jaws is thereby attained.
This object is achieved by provision of a rotatable sleeve forward of the switch release member, the sleeve being connected to the actuation rod so that rotation of the sleeve causes rotation of the jaws. The sleeve is preferably provided with radial projections dimensioned to define finger engaging recesses between adjacent projections. In this way the rotation of the jaws is responsive without any slackness to the movement of a surgeon""s finger.
A connection for engagement of the forceps to a diathermy power supply may be provided. In preferred embodiments of this invention the diathermy connection member is disposed on the lower side of the mounting core. In this way the power cable may pass unobtrusively beneath the surgeon""s wrist and under the arm, rather than over the hand as in previously known arrangements. The diathermy connection extends in a plane generally parallel and below the finger engaging bow portions of the handle.